The Mazda FE-DOHC was the DOHC variant of the FE. The official Mazda engine codes are FE-DE and FE-ZE, depending on output level. It is still commonly called the FE3 because of its head castings. The FE-DOHC shares the same dimensions as the original FE-SOHC, including the square 86 mm bore × stroke and it has an ideal 1.74 rod/stroke ratio. The FE-DOHC is usually identified by a gold-coloured cam cover, however not always. There were at least five different FE-DOHC engines available with various compression ratio, camshaft and ECU tuning combinations, however none were fitted with a turbocharger from the factory. Despite this, the FE-DOHC is already built for turbo with large forged connecting rods, large journal dimensions, oil cooler, piston oilers, web-stiffened block with main girdles. This robust engine design is a favourite of tuners who are aware of its capability because it already has a high-power capacity perfect for custom turbo jobs. As much as 600 whp has been seen on a stock engine. The common FE-DOHC crankshaft is cast while the forged crankshaft is fitted to the aluminum sump engines with both the main bearing braces and the main bearing girdle plate. In European 10.0:1 compression, non-catalytic trim, the FE-DOHC produces 148 ps at 6000 rpm and 133 lb/ft at 4000 rpm. The 9.2:1 compression, catalytic converter version produces 140 ps. The Japanese domestic market variants produce anywhere between 145 ps and 165 ps. The only vehicle with 165ps was the 96-97 Capellas Wagons, FX or FX Cruising. They had different tail lights to the earlier wagons.
Applications
The FE-DOHC was a European and Japanese market engine only, and as such was only ever delivered in vehicles by Mazda to countries in those markets, with the exception of New Zealand who also received European market models. The engine was first fitted to the GD model 1988-1992 626 GT, 1987-1991 Capella and the 626 Coupe GT 2.0i/Capella C2 GT-X and GT-R. In South Africa, Samcor who built Mazdas under licence also fitted the FE-DOHC engine to the Mazda 323 from 1991 to 1994. Alongside the sedan, hatch and coupé models the FE-DOHC was also being used in the GV wagon, which ran until 1997. The rest of the world received the FE-DOHC in the 1995–2003 Kia Sportage, built by Kia under license. Kia first introduced the engine in March 1992, when they installed it in the Kia Concord, a license built version of the 1982 Mazda Capella. The Sportage variant was reconfigured for rear-wheel drive configuration with long single-runner intake manifold, low-duration cams and exclusively in the low compression ratio of 9.2:1.
Different Models
Head and valvetrain
The Mazda FE-DOHC uses a wide-angle, DOHC, belt-driven valvetrain configuration with flat-tappet 33 mm HLA bucket lifters. It is a non interference design. There are two valve springs per valve and four valves per cylinder. While a dual valve spring configuration is used, the stock springs are fairly low-sprung. Low spring rates were chosen for fuel efficiency and increased valvetrain longevity, and low friction with the dual valve springs for the reduction of harmonics and increased valve stability.
Camshafts
The Mazda FE-DOHC came with several different camshaft profiles from the factory. As such there were several camshaft combinations available.
Camshaft
Lift
Duration
FE5A
8.855
250°
FE3N
8.852
245°
FEAP
8.650
230
KO13
?
?
F8K1
6.800
225
The F8K1 was the intake camshaft for the F8-DOHC, only listed due to family ties. The combinations available:
The FE-DOHC featured Mazda's VICS system, short for Variable Inertia Control System, a variable intake setup to optimize runner length and resonance at different engine speeds. Much like Toyota's Acoustic Control Induction System, it had two sets of intake runners, a long set for low-medium RPMs, and a short set for high RPMs. It was operated by a vacuum solenoid based on the engine's current speed, actuating a pair of butterflies inside the manifold to open or close the short runners past 5400 RPM. This system has been used on many Mazda engines since including the BP. The K-series V6 engines used a different principle to the same effect dubbed VRIS. Two versions of the VICS intake system exist, one has steeper straighter runners than the other, which is kinked for vehicle packaging reasons. VICS was not present on the F8-DOHC or Kia version of the FE-DOHC, both of which use a conventional intake manifold design.
The head gasket used on the Kia version can be sourced in North America, but the builder must note that the coolant passage holes are configured for a RWD cooling system. Attempting to use the RWD head gasket in FWD cooling configuration will result in improper flow and can result in overheating of cylinder #4.
